We have been developing kits to
photograph insects in flight since about 1975, back
in the days of film cameras and complicated home-built flash
units to get the requisite
short duration multiple flashes at the power required for 64 ISO
speed film.Below is a photograph of the current state of our art.
A cover fits over it for storage or
transport. For scale, the base (almost the width of the first
image) is 1.13 metres long.

The black rectangular item just
right of centre is the normal trigger beam with
a pair of IR LEDs (Infra-red Light Emitting Diodes) and sensor
at the tip.
We can slide the box across the 'stage'to
allow for the insect's speed of flight.
The operator sits behind the sliding boxand
tries to tease insects with soft paint brushes
to fly in the wanted direction.A bright
window in the wanted flight direction is a big helpexcept for some species of moth.

Inside the white box is a another
beam break (5 IR LED/sensor pairs) occasionally
used for different views. This used to be our primary flight
direction (towards
the camera at the right) but we get more flights and better
images with the
insects flying across the 'stage'. The setup is large enough to
include
the whole of the UK largest Dragonflies with a bit of margin.

The camera is on a mini sliding
mount looking left into the dark box but
focus locked onto the centre-line marked in white just below the
centre of the
first image.

There are 3 flashguns all
electrically (not radio or 'slaved') connected to the
camera:-

The obvious gun on
the right providing the main light.

Under the camera is a 'fill'
flash tucked under the camera on its side with
a wide angle diffuser

Finally a 'background' flash
inside the big white box used to illuminate a
painted sky.

All of the guns run at very reduced
power, typically 1/32 (3% of
maximum power) in
order to get a very short flash to freeze the wing motion.
Details later.

The camera is set at X-sync
speed, F29 (very small for maximum depth of focus)
fast multi-frame and mirror locked up. The control electronics
'holds down the shutter'
for the time required for the camera to take 3 frames (or
however many you want
and the flashguns can manage)

Bottom left is the control
electronics:-
A small PC of great vintage with parallel printer port
used as control signals. It runs
MSDOS from Windows 95 but with the right fudges for port
access and a PCMCIA
parallel port card you could use anything. If we built
the kit again now we would use
a 'Raspberry Pi' and write the software
in Python.

A
large steel case containing sense amplifiers for the beam break,
and power supplies.
This content of this box is about 20 years old &
can't be re-built the same.

A clearer view of the camera and
flashes 1 & 2.Flash 2 being on its side is fine because it is set to very wide angle.
Ref: P34_20090503_1524_933 Flight tunnel setup (ft1)(r+mb
Sample@768).jpg 126K

Another view of the kit configured
for strobe effects. Flashgun 1 is moved so as
not to illuminate the black velvet background, and is the only
flashgun used for this.
The exposure varies.
Ref: P34_20100917_1125_436 Flight Tunnel 1 multiflash strobe
configuration (orig)(r+mb Sample@768).jpg 148K

The electronics has been moved from
system to system and is very old.
The sense amplifier looks for sudden reductions in brightness
rather than
absolute levels so adjusts well for ambient light. This is the
decades old
schematic:-

Ref: Flight Tunnel 1 (FT1) Beam Sensor (web
size).gif

The setup is complex, and its a year
between main sessions, so we work from a check-list
that includes lots of setup details. The easiest way of
presenting this information seems to
be simply include the list with irrelevant stuff removed:-

Up the Tunnel: Frame and Focus in
front of barrier.
Across the Tunnel: Frame & Focus on Cross flight line.

Lens to Manual Focus (if used to set auto-set focus).
Lens to Stabilizer OFF (if present)

Expose test card using a beam break - check required guns flash.

REGULARLY:
Check flash 'ready' lights
WHILE DISMANTLING: All flashguns to OFF

Example images

Ref:
20090516_dc1_20090423_1345_185+1357_199 ft1 orange-tip butterfly
male flying over red campion (montage)(r+mb id@576).jpg
Only the orange tip butterfly male (shown here) sports the
orange tip that gives the
species it's name. The female does share the delicate green
tracery with her mate.
The insect and plants are often photographed separately with
exactly the same
setup (and choosing a suitable plant for the insect) and then
montaged together
as indicated in the filename.

This image is taken as a single exposure using a
strobe light - a very fast flash with the shutter held open.
80Hz means 80 flashes a second, so the image below last for
about 1/10th second. These have to be photographed
against an extremely black background (typically 20 flashes hit
it) and are not photo montages but made
'in the camera' with the images appearing to be transparent.